Method, system for obstacle detection and a sensor subsystem

ABSTRACT

The disclosure is related to a method and a system for obstacle detection adapted to a self-guiding machine. The method is performed in the system including a controller for driving the system, a light emitter, a light sensor, an image processor and a central processor. The light emitter and the light sensor are set apart at a distance. When the light emitter emits an indicator light being projected onto a path the self-guiding machine travels toward, the light sensor senses the indicator light. An image containing the indicator light is generated. After analyzing the image, at least one feature of the indicator light being sensed can be obtained and used to obtain a spatial relationship between the self-guiding machine and an obstacle. The spatial relationship allows the system to determine if the self-guiding machine will collide with a wall or fall from a cliff.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The disclosure is generally related to a technology for detectingobstacle, and in particular to a method for detecting an obstacle suchas a cliff that is on the path of a moving machine, a system forimplementing the method, and a sensor subsystem thereof.

2. Description of Related Art

A self-guiding device, e.g. an automatic vehicle or an automatic robotcleaning machine, should avoid colliding with the other things orfalling from a height. To avoid colliding with a wall, the self-guidingdevice requires a proximity sensor to determine a distance to the wallin order to avoid the collision. A conventional proximity sensor is suchas radar, ultrasonic sensor, or a light (infrared ray) sensor that is asensor able to find out the presence of any nearby object without aphysical contact.

For example, the ultrasonic sensor is utilized to emit ultrasonic wavesand receive the reflected waves for determining the front article thatreflects the ultrasonic waves. The time difference between the times foremitting and receiving can be used to determine the distance. For cliffdetection, a cliff sensor mounted at the bottom of the self-guidingdevice utilizes an infrared ray or ultrasonic waves to detect thepresence of a floor under the device by measuring the reflected orscattered infrared ray or waves from the surface of the floor.Therefore, such the cliff sensor can prevent the device from travelingover the cliff when the cliff sensor detects itself moves over thecliff.

When the self-guiding device is able to detect the obstacle, e.g. thewall or the cliff, its controller can conclude the sensed data andinstruct a driving system of the self-guiding device to stop the deviceor avoid the obstacle when it approaches or arrives the obstacle.

SUMMARY OF THE INVENTION

For further understanding of the instant disclosure, reference is madeto the following detailed description illustrating the embodiments ofthe instant disclosure. The description is only for illustrating theinstant disclosure, and not for limiting the scope of the claim.

One of the objectives of the method and the system for obstacle devicein one aspect of the disclosure is to detect an obstacle on the path aself-guiding machine travels. The process of obstacle detection isperformed in the self-guiding machine when it travels around an area. Analgorithm operated in the self-guiding machine is used to process thedata that is generated by a sensor subsystem installed in the machine.

According to one of the embodiments, the sensor subsystem of the systemfor performing the obstacle detection includes a light emitter and alight sensor. The light emitter emits a type of an indicator light, andthe light sensor captures one image at one time or a series of imagescontaining the indicator light for a period of time. In one aspect ofthe present disclosure, the information extracted from the image can beused to estimate a distance to the obstacle. In another aspect of thepresent disclosure, a change occurring in the series of images can beused to determine if the self-guiding machine approaches the obstacle,and the self-guiding machine can process an avoidance measure in orderto avoid the risk.

The indicator light emitted by the light emitter is such as a linearlight projected onto the area in front of the self-guiding machine. Thelight sensor can capture an image containing the linear light. Throughan image analysis process, the captured linear light renders theinformation that is used to determine the distance to the obstacle, orhow close it approaches the obstacle.

More, the method for obstacle detection can be adapted to a self-guidingmachine that has a light emitter and a light sensor. The light emitterand the light sensor are preferably set apart at a distance. The lightemitter emits an indicator light being projected onto a path theself-guiding machine travels toward, and the light sensor senses theindicator light projected onto the path so as to generate an imagecontaining the indicator light.

After analyzing the image, at least one feature of the indicator lightbeing sensed can be obtained. Then a spatial relationship between theself-guiding machine and an obstacle can be obtained in response to theat least one feature of the indicator light being sensed. This spatialrelationship allows the self-guiding machine to compute a distancebetween the self-guiding machine and the obstacle, and determine if theself-guiding machine will collide with the obstacle when compared with acollision threshold, or determine if the self-guiding machine will falldue to the obstacle when compared with a falling threshold.

According to one further embodiment, a system for obstacle detection isprovided. The system installed in a self-guiding machine includes acontroller, a light emitter, a light sensor, an image processor and acentral processor. The image processor is used to generate an imagecontaining the indicator light that is projected onto the path. Acentral processor is used to perform the method for obstacle detection.

Further, a sensor subsystem is provided in the system for obstacledetection. In one embodiment, the sensor subsystem mainly includes alight emitter, a light sensor, and an image processor that are used toemit the indicator light projected onto a path, sense the indicatorlight, and render the image containing the indicator light. The image ofindicator light is provided for the system of the self-guiding machineto analyze and obtain a spatial relationship between the self-guidingmachine and the obstacle.

More, the system obtains the spatial relationship that allows thecentral processor to compute a distance between the self-guiding machineand the obstacle, and determine if the self-guiding machine will collidewith the obstacle when compared with a collision threshold stored in amemory of the system, or determine if the self-guiding machine will falldue to the obstacle when compared with a falling threshold stored in thememory. Further, when the self-guiding machine reaches the collisionthreshold or the falling threshold, the central processor generates asignal for instructing the controller to drive the self-guiding machineto avoid the obstacle.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 shows a schematic diagram using a top view to depict acircumstance that a self-guiding machine approaches an obstacle in oneembodiment of the present disclosure;

FIG. 2 shows a schematic diagram depicting a circumstance that aself-guiding machine is in front of a cliff in one embodiment of thepresent disclosure;

FIG. 3 shows another schematic diagram depicting a perspective view of acircumstance that the self-guiding machine is in front of a wall in onefurther embodiment of the present disclosure;

FIG. 4A and FIG. 4B are the schematic diagrams showing a self-guidingmachine approaches a wall in one embodiment of the present disclosure;

FIG. 5A and FIG. 5B are the schematic diagrams showing a self-guidingmachine approaches a cliff in one further embodiment of the presentdisclosure;

FIG. 6A through FIG. 6D are the schematic diagrams showing aself-guiding machine approaches an obstacle with a height from a groundin one embodiment of the present disclosure;

FIG. 7 shows circuit blocks of a system for obstacle detection accordingto one embodiment of the present disclosure;

FIG. 8 shows a schematic diagram depicting a change of the indicatorlight captured by a light sensor of a self-guiding machine approaching awall according to one embodiment of the present disclosure;

FIG. 9 shows a schematic diagram depicting a change of the indicatorlight captured by a light sensor of a self-guiding machine approaching acliff according to one embodiment of the present disclosure;

FIGS. 10A, 10B and 10C show examples of the received lights by aself-guiding machine that approaches an obstacle according to oneembodiment of the present disclosure;

FIG. 11 shows a schematic diagram depicting a circular indicator lightprojected on a wall where a self-guiding machine approaches in oneembodiment of the present disclosure;

FIG. 12 shows a flow chart describing a process for obstacle detectionadapted to a self-guiding machine in a one embodiment of the presentdisclosure;

FIG. 13 shows a flow chart describing a process for obstacle detectionadapted to a self-guiding machine in a one further embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The aforementioned illustrations and following detailed descriptions areexemplary for the purpose of further explaining the scope of the instantdisclosure. Other objectives and advantages related to the instantdisclosure will be illustrated in the subsequent descriptions andappended drawings. In addition, for ease of illustration, similarreference numbers or symbols refer to elements alike.

The disclosure is related to a method and a system for obstacledetection adapted to a self-guiding machine. The self-guiding machine issuch as an autonomous vehicle or an autonomous cleaning robot that cannavigates an area automatically. The method allows the self-guidingmachine to sense and identify an obstacle in front of the machine, andthen drives the self-guiding machine to avoid the obstacleautomatically. The system for obstacle detection is exemplified as asensor subsystem that essentially includes a light emitter and a lightsensor that can be installed in the self-guiding machine.

It is featured that the light emitter and the light sensor are set apartat a distance in a horizontal direction, and the light emitter and thelight sensor can be disposed at the same or different horizontal levelof position. The light emitter may utilize a Laser or an LED to be alinear light source that emits a linear light as the indicator light, oralternatively emits a certain area of light as the indicator light. Thelight sensor is used to sense the linear light or the certain area oflight that is projected onto a path the self-guiding machine travelstoward.

Further, one of the objectives of the method and the system for obstacledevice in one aspect of the disclosure is to detect the obstacle, e.g. awall, a cliff, or a floating obstacle, on the path the self-guidingmachine travels. The method can be implemented by an algorithm operatedin the system for obstacle detection. The self-guiding machine canitself process the data that is generated by the sensor subsystem andperform an avoidance measure.

Reference is made to FIG. 1 showing a schematic diagram that uses a topview to depict a circumstance that a self-guiding machine approaches anobstacle in one embodiment of the present disclosure.

A self-guiding machine 10 shown in the diagram can be an autonomousrobot, e.g. an autonomous cleaning device that navigates an area withvarious terrains. A system for obstacle detection is installed in theself-guiding machine 10 for sensing the obstacle on a path theself-guiding machine 10 travels toward. The system can exemplarilyinclude a sensor subsystem that essentially includes a light emitter101, a light sensor 102 and a processing circuitry. The diagram alsoshows the light emitter 101 and the light sensor 102 that are set apartat a distance from each other in a horizontal direction. It is notedthat the light emitter 101 and the light sensor 102 are not necessary tobe disposed at the same horizontal level of position.

The light emitter 101 exemplarily utilizes a Laser or an LED to be alight source to emit a linear light 103. The linear light 103 may beformed by the light source through a specific lens. When theself-guiding machine 10 travels, the linear light 103 is continuouslyprojected onto a scene, e.g. a ground 19 or any surface of any terrain,in front of the self-guiding machine 10. For example, when theself-guiding machine 10 travels toward a wall 18 that forms the obstacleat a distance ‘d’ from the self-guiding machine 10, the linear light 103acting as an indicator light is projected onto both the wall 18 and theground 19. A border 15 between the ground 19 and the wall 18 divides thelinear line 103 into a first segment, i.e. the lower segment, and asecond segment, i.e. the upper segment, of the indicator light beingsensed. The light sensor 102 is such as a camera that has a field ofview which is indicated by two dotted lines drawn in the diagram forcapturing an image. It is noted that the field of view of the lightsensor 102 should cover the indicator light 13 for effectively detect astatus of the self-guiding machine 10. The light sensor 102 isconfigured to sense the linear light 103 and capture an image containingthis linear light 103. When the system for obstacle detection isoperated in the self-guiding machine 10, a length ‘s’ of the lowersegment of the linear light 103 can be sensed by the light sensor 102.For example, a length ‘s’ sensed by the light sensor 102 can be used tobe an indicator used to determine the distance ‘d.’

It should be noted that the distance ‘d’ between the self-guidingmachine 10 and the wall 18 can be determined based on the length ‘s’that is sensed by the light sensor 102. Further, a horizontal positionof the upper segment of the linear light 103 can also be the indicatorused to determine the distance ‘d.’ Furthermore, in one embodiment, thelight sensor 102 can continuously sense the indicator light, and thesystem can accordingly generate a series of images containing theindicator light. If any change of the length ‘s’ appearing in the imageof the lower segment of the linear light 103 or of the position/lengthof the upper segment of the linear light 103 has found in the series ofimages, the change allows the system to acknowledge that theself-guiding machine 10 is approaching or leaving the wall 18.

Therefore, in addition to the length or position of the indicator lightcaptured by the light sensor 102, the any change of the aforementionedlength or position of the indicator light obtained from the series ofimages can also be used to determine a status of the self-guidingmachine 10, e.g. a moving trend of the self-guiding machine 10. Thesystem for obstacle detection also establishes a warning mechanism forthe self-guiding machine 10 according to a spatial relationship betweenthe self-guiding machine 10 and the wall (18).

One further type of the obstacle is a cliff. Reference is made to FIG. 2showing a schematic diagram depicting a circumstance that a self-guidingmachine is in front of a cliff in one embodiment of the presentdisclosure.

The self-guiding machine 10 travels over a plane 20 of a terrain, e.g. atable or a ground and toward a cliff 22. The cliff 22 can be formed by avertical section of the table or a downward stairway of the ground. Thelight emitter 101 of the self-guiding machine 10 continuously emits anindicator light 103′ projected onto the way the machine 10 travels over.The indicator light 103′ of the present example appears to be a linearlight when the light emitter 101 emits the linear light in a verticaldirection. The diagram utilizes section lines to present a range of theemitting light. The light sensor 102 senses the indicator light 103′within its field of view and the system generates an image containingthe indicator light 103′.

According to the present embodiment, the indicator light 103′ appears tobe cut by an edge 15′ between the plane 20 and the cliff 22. The cutindicator light 103′ has been shown in the image captured by the lightsensor 102. The indicator light 103′ shows an obstacle, e.g. the cliff22, will be met by the self-guiding machine 10 and its length or aslope/angle sensed by the light sensor 102 allows the system todetermine a distance between the self-guiding machine 10 and theobstacle indicated by the edge 15′. Therefore, when the system forobstacle detection acknowledges the cliff 22 is on the way theself-guiding machine 10 travels over, the system will instruct theself-guiding machine 10 to avoid this obstacle.

FIG. 3 shows another schematic diagram depicting a perspective view of acircumstance that the self-guiding machine is in front of a wall in onefurther embodiment of the present disclosure.

In the diagram, the self-guiding machine 10 travels over a ground 30 andtoward a wall 32. The light emitter 101 of the self-guiding machine 10emits a linear light as an indicator light in a vertical direction. Therange of the emitting light covers both the ground 30 and the wall 32 infront of the self-guiding machine 10.

When the self-guiding machine 10 traveling over the ground 30 approachesthe wall 32, the length of an indicator light 103″ indicates how closethe self-guiding machine 10 approaches the wall 32. In another aspect ofthe method for obstacle detection of the present disclosure, a slope orangle of the indicator light 103″ can also show the spatial relationshipbetween the self-guiding machine 10 and the wall 32; alternatively, aposition of segment of the indicator light on the wall 32 can also bethe indicator for depicting the spatial relationship.

According to the above embodiments of the method and the system forobstacle detection, a linear light emitted by the light emitter of thesystem installed in the self-guiding machine acts as an indicator lightand the feature(s) of the indicator light can be used to determine aspatial relationship between the self-guiding machine and an obstacle,e.g. a wall or a cliff. Therefore, the system can effectively preventthe self-guiding machine from colliding with the wall or falling fromthe cliff. Since the light emitter and the light sensor of the systemare set apart at a distance, i.e. preferably a horizontal distance, thefeatures of the indicator light sensed by the light sensor can beanalyzed for rendering the information such as a length, a position, aslope/angle and/or an area. At least one of the features is sufficientto be used to determine the spatial relationship between theself-guiding machine and the obstacle. Further, a change of one of thefeatures between at least two images having the indicator light can beused to render a moving trend of the self-guiding machine. This movingtrend allows the system to timely issue an alarm of collision or fallingto the self-guiding machine.

FIG. 4A and FIG. 4B are the schematic diagrams showing a change of oneof the features that allow the system to issue the alarm of collision toa self-guiding machine when it approaches a wall.

In FIG. 4A, this lateral view diagram shows a self-guiding machine 40such as an autonomous vehicle travels over a ground 43. A light emitterof the system for obstacle detection installed in the self-guidingmachine 40 emits an indicator light to the front of the machine 40. Thelight emitter has a range of emission 42 and its emitted light isconfined to this range. The indicator light can be sensed by a lightsensor of the system. When the self-guiding machine 40 is in front of awall 44 within a specific distance that is available for the system todetermine a spatial relationship between the self-guiding machine 40 andthe obstacle, the indicator light is projected onto both the ground 43and the wall 44. While the indicator light is sensed by the light sensorwithin its field of view, a first segment having a length ‘40 a’ and asecond segment having a length ‘40 b’ are respectively computed byanalyzing the image containing all or part of the indicator light.

While the self-guiding machine 40 approaches the wall 44, reference ismade to FIG. 4B, it shows the range of emission 42′ becomes smaller thanthe previous status. Simultaneously, the indicator light sensed by thelight sensor has been changed. For example, the length of the firstsegment of the indicator light projected onto the ground 43 has beenchanged to “40 a′” and the length of the second segment of the indicatorlight projected onto the wall 44 has been changed to “40 b′.” Therefore,the system for obstacle detection utilizes the feature of the length ofthe first segment or the second segment of the indicator light beingsensed to determine the distance between the self-guiding machine 40 andthe obstacle, e.g. the wall 44.

Furthermore, when the system captures two or more images containing theindicator light, a change of at least one feature of the indicator lightcan be used to obtain a moving trend of the machine and to determine ifthe self-guiding machine approaches the obstacle.

FIG. 5A and FIG. 5B are the schematic diagrams showing a change of oneof the features that allow the system to issue a falling alarm to aself-guiding machine when it approaches a cliff

In FIG. 5A, the lateral view diagram shows a self-guiding machine 50travels over a ground 53 including a cliff 54 at a distance away. Alight emitter of the system for obstacle detection in the self-guidingmachine 50 emits an indicator light to the front of the machine 50. Theindicator light can be sensed by a light sensor of the system. When theself-guiding machine 50 is at a distance in front of the cliff 54, asegment of the indicator light is projected onto the ground 53 and therest of the indicator light is cut by an edge of the ground 53 due tothe cliff 54. The indicator light projected onto the ground 53 leaves adistance ‘50 a’ to be sensed by the light sensor. While the indicatorlight is sensed by the light sensor within its field of view, thedistance ‘50 a’ is computed by analyzing the image containing all orpart of the indicator light.

While the self-guiding machine 50 approaches the cliff 54, reference ismade to FIG. 5B, the distance of the indicator light projected onto theground 53 becomes shorter. For example, the length of the indicatorlight sensed by the light sensor projected onto the ground 53 is ‘50 a’in FIG. 5A, and then the indicator light projected onto the ground 53has been changed to “50 a′.” Therefore, the system for obstacledetection also utilizes the feature of the length of the indicator lightbeing sensed to determine the distance between the self-guiding machine50 and the obstacle, e.g. the cliff 54.

Similarly, when the system captures two or more images containing theindicator light, a change of length of the indicator light can be usedto obtain a moving trend of the machine and to determine if theself-guiding machine approaches the obstacle.

FIG. 6A through FIG. 6D are the schematic diagrams showing aself-guiding machine approaches a floating obstacle with a height from aground in one further embodiment of the present disclosure.

In FIG. 6A, a self-guiding machine 60 travels over a ground 63 andapproaches a floating obstacle 64. A light sensor of the self-guidingmachine 60 senses an indicator light, for example a linear light,emitted by a light emitter of the system installed in the self-guidingmachine 60. When the self-guiding machine 60 is in front of the floatingobstacle 64 that is with a height from the ground 63, the indicatorlight within a range of emission 62 of the light emitter of the systemforms two segments, i.e. a segment of the indicator light is projectedto the ground 63 and the other segment of the indicator light isprojected to the floating obstacle 64. The segment of the indicatorlight projected to the floating obstacle 64 forms a light with a length‘60 b’ sensed by the light sensor.

As the system for obstacle detection is in operation, the light sensorof the system is driven to capture an image with the segment ofindicator light projected onto the ground 63 and the other segment ofthe indicator light having a length ‘60 b’ projected onto the floatingobstacle 64. The image can be referred to a frame 66 shown in FIG. 6B.The frame 66 shows at least two features extracted from the imagecaptured by the light sensor. A first segment 60 a shown in the frame 66indicates the segment of indicator light projected onto the ground 63. Asecond segment 60 b shown in the frame 66 indicates the segment ofindicator light projected onto the floating obstacle 64.

Next, in FIG. 6C, the self-guiding machine 60 is getting close to thefloating obstacle 64 over the ground 63. The floating obstacle 64 causeschanging the range of emission 62′ of the light emitter of the system.Both the segments of indicator light respectively projected onto theground 63 and the floating obstacle 64 have been changed. For example,the length of the segment of the indicator light projected onto thefloat obstacle 64 has been changed to length “60 b′” due to the spatialrelationship between the self-guiding machine 60 and the floatingobstacle 64 has been changed.

The image captured by the light sensor can be referred to the frame 66′shown in FIG. 6D. When the self-guiding machine 60 approaches thefloating obstacle 64, both features of the first segment 60 a′ and thesecond segment 60 b′ have been changed. It shows both the length and theslope of the first segment 60 a′ have been changed. For example, thelength of the first segment 60 a′ is shorter than the length of thefirst segment 60 a, and the slope thereof also changes when theself-guiding machine 60 approaches the floating obstacle 64. Further,both the length and the position of the second segment 60 b′ have beenchanged. For example, the length of the second segment 60 b′ is shorterthan the length of the second segment 60 b, and the position of thereofshifts to the left in the same instance.

According to one of the embodiments, a sensor module essentiallyincludes a light emitter and a light sensor that are set apart at adistance. The light emitter emits a type of an indicator light, and thelight sensor captures one image at one time or a series of imagescontaining the indicator light for a period of time. The indicator lightemitted by the light emitter is such as a linear light, a circular lightor any shape of light projected onto the way the self-guiding machinetravels toward. The light sensor can capture an image containing theindicator light. Through an image analysis process, the informationextracted from the indicator light being captured is used to determine aspatial relationship between the self-guiding machine and an obstacle.The spatial relationship allows the system to instruct the drivingsystem of the self-guiding machine to avoid risk of collision orfalling.

FIG. 7 shows circuit blocks of a system for obstacle detection accordingto one embodiment of the present disclosure.

The system for obstacle detection with a sensor subsystem that hascapability of data processing since it has its own processor and memory.The sensor subsystem is used to collect the environmental informationaround it and to process the environment information for rendering aprotection mechanism. The environment information is such as images ofenvironment around the self-guiding machine adopting this system. Theenvironmental information allows the system to determine if theself-guiding machine will meet any risk of damage.

The functions provided by the system are implemented by the circuitcomponents shown in the diagram. The system includes a controller 701that is in charge of controlling operations of the other circuitcomponents for operating the system. The controller 701 is used to drivea light emitter 702 to emit the indicator light, and also control alight sensor 705 to sense the light signals within its field of view. Inan exemplary example, the indicator light such as a linear light, acircular light or any type of the indicator light can be controlled tofunction in a full-time manner or periodically. The system includes thelight emitter 702 coupled to the controller 701. The light emitter 702has a light source and its driving circuit and is used to emit anindicator light through a requisite optical component and/or a windowthat is mounted on a surface of the self-guiding machine. The opticalcomponent is such as a lens that can be used to guide the indicatorlight to be a linear light, a circular light or any shape of the light.The system includes the light sensor 705 coupled to the controller 701.The light sensor 705 set apart at a distance from the light emitter 702is used to sense the indicator light emitted by the light emitter 702.Then the scene in front of the self-guiding machine is captured by thelight sensor 705 and then transmitted to an image processor 704 of thesystem for generating an image containing the indicator light. The imageprocessor 704 is coupled to the light sensor 705 and is used to generatethe image. The image is temporarily buffered, for example, in a memory706.

According to a circuitry planning in one embodiment of the disclosure,the light emitter 702, the light sensor 705 and the image process 704form a sensor subsystem installed in the self-guiding machine. Thesensor subsystem is in charge of generating the indicator light andrendering the image of the indicator light. Therefore, the self-guidingmachine can use at least one feature of the indicator light being sensedto obtain a spatial relationship between itself and an obstacle when theself-guiding machine approaches the obstacle on its path.

After that, at least one feature of the indicator light involved in theimage is processed by a central processor 703 that is coupled to theimage processor 704 and the controller 701. The central processor 703 isused to perform the method for obstacle detection. In one embodiment ofthe present disclosure, the memory 706 coupled to the central processor703 acts as a system memory or storage that can be used to store theinstructions for performing the functions provided by the system, forexample the method for obstacle detection. The method performed by thecentral processor 703 primarily includes analyzing the image containingthe indicator light sensed by the light sensor 705, obtaining at leastone feature of the indicator light being sensed, and obtaining a spatialrelationship between the self-guiding machine and an obstacle inresponse to the at least one feature of the indicator light being sensedwhen the self-guiding machine approaches the obstacle on its path.

According to one embodiment of the present disclosure, the informationextracted by the sensor subsystem from the image having the indicatorlight can be used to estimate a distance to an obstacle. Further, thespatial relationship, e.g. the distance between the self-guiding machineand the obstacle, allows the system to determine if the self-guidingmachine will be in any dangerous situation, for example colliding with awall or falling from a cliff. In an exemplary example, the controller701 of the system is coupled to a machine driver 708 that links to adriving system of the self-guiding machine adopting this system. Whenthe system determines that an obstacle exists at a distance from theself-guiding machine, the controller 701 generates a signal forinstructing a machine driver 708 for responding to the obstacle.

In one further embodiment, the light sensor 705 can also continuouslycaptures a series of images covering the indicator light, and a changeoccurring in the series of images can be found and used to determine ifthe self-guiding machine approaches the obstacle. The self-guidingmachine can process an avoidance measure in order to avoid the risk.

As a matter of illustration, the following figures are given as a guideto describe the method for obstacle detection in accordance with theembodiments described above.

FIG. 8 shows a schematic diagram depicting a change of the indicatorlight captured by a light sensor of a self-guiding machine approaching awall according to one embodiment of the present disclosure.

The system installed in a self-guiding machine 80, 80′ is exemplified asthe sensor subsystem essentially including a light emitter 801, 801′ anda light sensor 802, 802′. The self-guiding machine 80, 80′ acts asautonomous vehicle including a computer that drives the light emitter801, 801′ to emit indicator light, integrates data received by the lightsensor 802, 802′ and then processes the data for acquiring the terraininformation regarding the path in front of the self-guiding machine 80.

As the diagram shows, the self-guiding machine 80 depicted by a solidline is at a first position when it travels over a ground 80. Theself-guiding machine 80 includes the light emitter 801 and the lightsensor 802. The light emitter 801 emits an indicator light 803. Theindicator light 803 depicted in the diagram is based on the image sensedby the light sensor 802 in its viewing angle. The diagram shows theindicator light 803 has a turning point that divides the indicator light803 into two segments due to a border between the ground 83 and the wall84.

The self-guiding machine 80 then moves to a second position closer tothe wall 84 and is marked as the self-guiding machine 80′ that isdepicted by a dotted line. At the second position, the light emitter801′ still emits an indicator light 803′ and the light sensor 802′receives the indicator light 803′ and generates another image.Similarly, the indicator light 803′ depicted in the diagram is based onthe image sensed by the light sensor 802′ in its viewing angle. Theborder of between the ground 83 and the wall 84 causes the indicatorlight 803′ to have another turning point that divides the indicatorlight 803′ into two segments.

This exemplary example shows several changes of the indicator light 803,803′ projected onto both the ground 83 and the wall 84 when theself-guiding machine 80, 80′ travels toward the obstacle, i.e. the wall84. It should be noted that the light emitter 801, 801′ emits a linearlight and the light sensor 802, 802′ senses the light within its sensingrange confined by its viewing angle. The diagram shows when the linearlight is projected onto both the ground 83 and the obstacle, i.e. thewall 84, at least one feature of the indicator light 803, 803′ can befound by analyzing the image containing the indicator light 803, 803′.For example, a length, as one of the features, of a first segment of theindicator light 803, 803′ projected onto the ground 83 becomes shorterwhen the self-guiding machine 80, 80′ is closer to the wall 84. Further,a slope can act as another feature for detecting the obstacle since theimage being sensed shows a slope of the first segment of the indicatorlight 803, 803′ becomes larger when the self-guiding machine 80, 80′ iscloser to the wall 84. Furthermore, the shorter length or the left-shiftposition of a second segment of the indicator light 803, 803′ projectedonto the wall 84 can also act as one of the features to detect theobstacle when the self-guiding machine 80, 80′ is closer to the wall 84.Therefore, in this exemplary example, a length of the first segment orthe second segment, a position of the second segment and/or aslope/angle of the first segment can be regarded as the feature(s)allowing the system to detect the obstacle.

FIG. 9 shows another schematic diagram depicting a change of theindicator light captured by a light sensor of a self-guiding machineapproaching a cliff according to one embodiment of the presentdisclosure. The present example shows the self-guiding machine 90, 90′travels over a ground 94 and will meet an obstacle, i.e. a cliff, andthe system in the self-guiding machine 90, 90′ is required to detect theobstacle and avoid falling.

The diagram shows a self-guiding machine 90 depicted by a solid line isoriginally at a first position. A light emitter 901 of the self-guidingmachine 90 at the first position emits an indicator light (903, 904),and a light sensor 902 captures an image containing the indicator light(903, 904) in its viewing angle. The self-guiding machine 90 then movesto a second position closer to an edge 93 and is marked as theself-guiding machine 90′ depicted by a dotted line. At the secondposition, the light sensor 902′ senses the indicator light (903′, 904′)emitted by the light emitter 901′ of the self-guiding machine 90′ in aviewing angle. The edge 93 formed by the cliff cuts the indicator lightand the segment projected onto the ground 94 is marked as a firstsegment 903, 903′. It should be noted that the segment 904, 904′ of theindicator light being sensed not well connected to the first segment(903, 903′) is projected onto a distant wall with a distance from thecliff and is still sensed by the light sensor 902, 902′.

This exemplary example shows the length of the first segment 903, 903′of the indicator light being sensed by the light sensor 902, 902′becomes shorter and with larger slope when the self-guiding machine 90,90′ moves from the first position to the second position that is closerto the edge 93 of the cliff. Therefore, the feature(s) of the firstsegment 903, 903′ of the indicator light being sensed by the lightsensor 902, 902′ can be the information for the system to detect theobstacle, i.e. the cliff. The system accordingly determines if theself-guiding machine 90, 90′ approaches the edge 93 of the cliff.

FIGS. 10A, 10B and 10C show three frames of images depicting an exampleof the received lights by a self-guiding machine that approaches anobstacle at a distance of 20 cm, 10 cm and 5 cm.

FIG. 10A shows a frame 1001 with a width from pixel 0 to pixel 200. Theframe 1001 appears a light segment 1004 of indicator light projectedonto a path the self-guiding machine travels toward when theself-guiding machine is at 20 cm distance from an obstacle, e.g. a wallor a cliff. The frame 1001 further uses a dotted line 1005 to indicatethe position of the light segment projected onto the wall.

FIG. 10B shows another frame 1002 with the same width. The frame 1002appears a light segment 1006 of the indicator light projected onto thepath when the self-guiding machine is at 10 cm distance from theobstacle. The dotted line 1007 indicates the position of the lightsegment projected onto the wall. It is noted that the slope of the lightsegment 1006 is larger than the slope of the light segment 1004 shown inFIG. 10A; and as well the length of the light segment 1006 is shorterthan the length of the light segment 1004 shown in FIG. 10A since theself-guiding machine is getting close to the obstacle.

FIG. 10C shows one more frame 1003 with the same width. The frame 1003appears a light segment 1008 of the indicator light projected onto thepath when the self-guiding machine is at 5 cm distance from theobstacle. The dotted line 1009 indicates the position of the lightsegment projected onto the wall. Similarly, the slope of the lightsegment 1008 is larger than the slope of the light segment 1006 shown inFIG. 10B; and as well the length of the light segment 1008 is shorterthan the length of the light segment 1006 shown in FIG. 10B since theself-guiding machine is getting close to the obstacle.

On the other hand, according to the positions indicated by the dottedline 1005 of FIG. 10A, 1007 of FIG. 10B and 1009 of FIG. 10C, it isfound that the segment of indicator light projected onto the obstacle,i.e. the wall, gradually moves to the left as the self-guiding machineapproaches the obstacle. Therefore, the position of the light segmentalso acts as an indicator for indicating the spatial relationshipbetween the self-guiding machine and the obstacle.

The indicator light emitted by the light emitter of the system can alsobe a circular light. FIG. 11 shows a schematic diagram depicting acircular indicator light projected on a wall where a self-guidingmachine approaches in one embodiment of the present disclosure.

The circular indicator light projected on the wall is sensed by thelight sensor at a distance apart from the light emitter, and thereforethe circular indicator light being sensed and shown in the diagram getsa little distorted. The circular indicator light being sensed specifiesa reference point (1111, 1112) and is divided into a first segment (111,113), e.g. the lower area, and a second segment (112, 114), e.g. theupper area by a dividing line. The dividing line can be a border betweena ground and a wall or an edge of a cliff.

As the diagram shows, the solid circle indicates the self-guidingmachine is at a first position, and the dotted circle indicates theself-guiding machine is at a second position that is closer to theobstacle, e.g. the wall. It appears that both the areas of the firstsegment and the second segment of the dotted circle are smaller than thesolid circle when the self-guiding machine approaches the obstacle.Further, referring to the reference points 1111 and 1112 respective tothe solid circle and the dotted circle, it appears that the dottedcircle moves to the left relative to the solid circle as theself-guiding machine approaches the obstacle.

Therefore, the area and the position of the circular indicator light canact as the indicator for indicating the spatial relationship between theself-guiding machine and the obstacle.

When the system obtains the spatial relationship, the central processorof the system accordingly computes a distance between the self-guidingmachine and the obstacle, and determines if the self-guiding machinewill collide with the obstacle when compared with a collision thresholdstored in a memory of the system. Similarly, the spatial relationshipalso allows the system to determine if the self-guiding machine willfall due to the obstacle when compared with a falling threshold storedin the memory.

The system exemplarily described in FIG. 7 performs the method forobstacle detection adapted to a self-guiding machine. Reference is madeto FIG. 12 that shows a flow chart describing the method for obstacledetection in one embodiment.

In step S121, the light emitter of the system emits an indicator light,and in step S123 the light sensor of the system is used to senses theindicator light and generate an image. The light sensor is such as acamera that captures the image containing the indicator light within aviewing angle. The indicator light can reflect a spatial relationshipbetween the self-guiding machine and the obstacle when the indicatorlight can be projected onto the path including the ground and/or theobstacle the self-guiding machine travels over. The image processor ofthe system then analyzes the image for acquiring at least one feature ofthe indicator light being sensed, such as step S125.

According to the above embodiments, the feature can be a length, aposition, a slope and/or an area of the indicator light being sensed.Any of the features is provided for the central processor of the systemto compute the length, the position, and/or the slope regarding thelinear indicator light or the area regarding the circular indicatorlight. In step S129, the at least one feature allows the system todetermines a distance between the self-guiding machine installing thesystem and an obstacle.

The system can also find a moving trend of the self-guiding machineaccording to the change of the feature extracted from the indicatorlight being sensed for a period of time by the light sensor of thesystem. Reference is made to FIG. 13.

In step S151, the light emitter continuously emits an indicator lightprojected onto the ground and/or the obstacle in front of theself-guiding machine. In step S153, the light sensor is driven tocapture at least two different images containing the indicator lightwithin a time period. By analyzing the at least two images, in stepS155, the system can obtain at least one feature from individual image.The feature can also be the length, the position and/or the slopeobtained from the linear indicator light being sensed by the lightsensor, or the area obtained from the circular indicator light. In stepS157, any change of length, slope, position and/or area of the indicatorlights in both images within the time period can be obtained fordetermining the change of the spatial relationship between theself-guiding machine and the obstacle.

The change of the indicator light projected onto the ground and/or theobstacle can be used to determine the moving trend of the self-guidingmachine. The system accordingly can determine if the self-guidingmachine is getting close to any obstacle that it should be avoid.Therefore, the system can issue an alarm in advance for the self-guidingmachine.

To sum up the above embodiments, the method and the system for obstacledetection can be adapted to a self-guiding machine such as an autonomousvehicle or an autonomous cleaning robot. The system can acquire aspatial relationship between the self-guiding machine and the obstacleaccording to at least one feature extracted from an indicator lightprojected onto the path the self-guiding machine travels over. Thespatial relationship allows the self-guiding machine to compute adistance between the self-guiding machine and the obstacle so as todetermine if the self-guiding machine will collide with a wall, ordetermine if the self-guiding machine will fall from a cliff. Theinvention provides the self-guiding machine a solution to determine adistance from an obstacle and optionally to warn the self-guidingmachine when it approaches the obstacle. Further, the system canaccordingly instruct the driving system of the self-guiding machine toavoid the obstacle.

The descriptions illustrated supra set forth simply the preferredembodiments of the instant disclosure; however, the characteristics ofthe instant disclosure are by no means restricted thereto. All changes,alterations, or modifications conveniently considered by those skilledin the art are deemed to be encompassed within the scope of the instantdisclosure delineated by the following claims.

What is claimed is:
 1. A method for obstacle detection adapted to aself-guiding machine including a light emitter and a light sensor thatare set apart at a distance, comprising: the light emitter being a Laseror an LED to be a linear light source that emits a linear light as anindicator light and the indicator light being a vertical linear lightprojected onto a path the self-guiding machine travels toward; the lightsensor sensing the indicator light projected onto the path so as togenerate an image containing the indicator light; in the self-guidingmachine analyzing the image so as to obtain at least one feature that isa length, a position or a slope of the indicator light being sensed; andobtaining a spatial relationship between the self-guiding machine and anobstacle in response to the at least one feature of the indicator lightbeing sensed when the self-guiding machine approaches the obstacle onthe path; wherein, when the self-guiding machine approaches a floatingobstacle with a height from a ground and the indicator light isprojected to the floating obstacle, the vertical linear light issegmented into a first segment projected to the ground and a secondsegment projected to the floating obstacle, in which the second segmentof the light sensed by the light sensor is determined as the floatingobstacle in front of the self-guiding machine.
 2. The method as recitedin claim 1, wherein the spatial relationship allows the self-guidingmachine to compute a distance between the self-guiding machine and theobstacle.
 3. The method as recited in claim 1 wherein the linear lightis projected onto both the ground and the obstacle so as to form thefirst segment and the second segment of the indicator light which issensed by the light sensor when the self-guiding machine approaches awall, and the at least one feature of the indicator light being sensedis the length of the first segment or the second segment, the positionof the second segment and/or the slope of the first segment.
 4. Themethod as recited in claim 1, wherein the linear light is projected ontothe ground and being truncated by an edge of the ground when theself-guiding machine approaches a cliff, and the at least one feature ofthe indicator light being sensed is the length and/or the slope of theindicator light being projected onto the ground.
 5. A system forobstacle detection installed in a self-guiding machine, comprising: acontroller; a light emitter, coupled to the controller, being a Laser oran LED to be a linear light source that emits a linear light as anindicator light and the indicator light being a vertical linear lightprojected onto a path the self-guiding machine travels toward; a lightsensor, coupled to the controller, used to sense the indicator lightprojected onto the path, wherein the light emitter and the light sensorare set apart at a distance; an image processor, coupled to the lightsensor, used to generate an image containing the indicator light; acentral processor, coupled to the image processor and the controller,used to perform a method for obstacle detection comprising: analyzingthe image containing the indicator light sensed by the light sensor;obtaining at least one feature that is a length, a position or a slopeof the indicator light being sensed; and obtaining a spatialrelationship between the self-guiding machine and an obstacle inresponse to the at least one feature of the indicator light being sensedwhen the self-guiding machine approaches the obstacle on the path;wherein, when the self-guiding machine approaches a floating obstaclewith a height from a ground and the indicator light is projected to thefloating obstacle, the vertical linear light is segmented into a firstsegment projected to the ground and a second segment projected to thefloating obstacle, in which the second segment of the light sensed bythe light sensor is determined as the floating obstacle in front of theself-guiding machine.
 6. The system as recited in claim 5, wherein thesystem obtains the spatial relationship that allows the centralprocessor to compute a distance between the self-guiding machine and theobstacle.
 7. The system as recited in claim 6, wherein the methodperformed by the central processor further comprises instructing thecontroller to drive the self-guiding machine to avoid the obstacle whenthe self-guiding machine reaches the collision threshold or the fallingthreshold.
 8. The system as recited in claim 5, wherein the linear lightis projected onto both the ground and the obstacle so as to form thefirst segment and the second segment of the indicator light being sensedif the obstacle is when the self-guiding machine approaches a wall, andthe at least one feature of the indicator light being sensed is thelength of the first segment or the second segment, the position of thesecond segment and/or the slope of the first segment.
 9. The system asrecited in claim 5, wherein the linear light is projected onto theground and being truncated by an edge of the ground when theself-guiding machine approaches a cliff, and the at least one feature ofthe indicator light being sensed is the length and/or the slope of theindicator light being projected onto the ground.
 10. A sensor subsystemfor a self-guiding machine navigating an area, comprising: a lightemitter being a Laser or an LED to be a linear light source that emits alinear light as an indicator light and the indicator light being avertical linear light projected onto a path the self-guiding machinetravels toward; a light sensor used to sense the indicator lightprojected onto the path, wherein the light emitter and the light sensorare set apart at a distance; and an image processor, coupled to thelight sensor, used to render an image containing the indicator light;wherein the self-guiding machine uses at least one feature that is alength, a position or a slope of the indicator light being sensed toobtain a spatial relationship between the self-guiding machine and anobstacle when the self-guiding machine approaches the obstacle on thepath; when the self-guiding machine approaches a floating obstacle witha height from a ground and the indicator light is projected to thefloating obstacle, the vertical linear light is segmented into a firstsegment projected to the ground and a second segment projected to thefloating obstacle, in which the second segment of the light sensed bythe light sensor is determined as the floating obstacle in front of theself-guiding machine.
 11. The sensor subsystem as recited in claim 10,wherein the sensor subsystem is installed in an autonomous robot.